双喷嘴挡板伺服阀流固耦合特性分析及振动抑制

发布时间：2018-01-16 09:11

本文关键词：双喷嘴挡板伺服阀流固耦合特性分析及振动抑制　出处：《北京交通大学》2015年博士论文　论文类型：学位论文

【摘要】：摘要：电液伺服系统以传递功率大、响应速度快、控制精度高等特点,在航空、航天、船舶等国防工业领域占有举足轻重的地位。作为电液伺服控制系统中的核心部件,精密电液伺服阀机械结构复杂、精密度高,其自身稳定性、可靠性和快速性很大程度上决定了电液伺服系统的控制性能,甚至影响到航空航天飞行任务的成败。当进行启闭控制动作时,电液伺服系统内部流体激振常常产生自激现象,导致力矩马达及活塞产生较大的振动幅值,严重影响其正常工作特性甚至使用寿命。本文以某型航天用精密双喷嘴挡板电液伺服阀为研究对象,对电液伺服阀的流固耦合振动特性、诱发机理以及对整个系统控制的影响规律进行深入研究,以便构造合理的基础模型,进一步完善电液伺服阀基础理论体系,最后获取相应的控制措施来减小或抑制耦合振动。本文首先阐述本课题的研究背景,总结了国内外学者在流固耦合振动特性、研究方法、电液伺服系统振动的研究概况以及振动控制等方面的研究成果,分析并提出了流固耦合振动分析及控制中的关键问题,明确本文的研究方向、目的及意义,最后确定本文研究的技术路线。根据阀控电液伺服控制系统的基本工作原理,对电液伺服阀的静动态特性进行了深入分析,建立了双喷嘴挡板伺服阀的非线性数学模型,同时根据非线性微分控制理论,通过非线性状态反馈变换,将系统进行输入／输出线性化,并在此基础上对系统的零动态稳定性进行了深入分析。相较于基于工作点的基础增量线性化方法而言,所建的线性化数学模型将为分析流固耦合振动现象以及振动控制提供理论基础,新模型将更接近实际控制系统。伺服阀自激是由系统的非恒定流动引起,是流动参数阶跃变化时的动态过渡过程。电液伺服阀以喷嘴挡板为前置级驱动结构,其内部喷嘴射流流动速度快、剪切流动强、析出气穴多,流体激振引起的耦合振动往往造成伺服阀工作中产生高频啸叫。在本文中,结合流体力学的基本理论,以非线性电液伺服阀模型为基础,建立了喷嘴挡板间射流流场模型。同时通过现场试验,获取电液伺服阀射流流场的真实流动参数,最终给出前置级射流压力脉动、结构参数与高频自激振动三者之间的内在联系。伺服阀滑阀副组件作为伺服阀二级放大结构,流体通过阀口高速流入相对缓慢的阀腔流场中,形成具有较大速度梯度的自由剪切层,剪切分离处的微小扰动在传播过程中受剪切层不稳定性影响形成放大,并递经上下游壁反射诱发新的扰动,形成自激振动。本文采用流体振荡理论及流体行为方程数值方法,将流经管道的流体作为非线性参数系统,计算出各处的阀或者执行元件,当作流体运动的边界条件,计算了稳定界限,获得了方程组的精确解,最后基于其结构特点和工作特性的分析,提出了一种流固耦合半解析式数学模型。为了深入研究液压系统的运动状态和各项参数的分布规律,根据液压系统运动的实际情况和运动过程,以一维流体瞬变理论为基础,考虑油液压缩性对油液动量的改变,采用特征线分析方法,利用有限差分格式,对伺服阀控液压管路关机水击的进行数值分析,同时通过实验研究获取其管路动态特性,结果分析表明,该动态模型可以较好的描述管路系统的瞬变特性。最后通过研发电液伺服自激特性研究试验台,对其静动态以及流固耦合振动特性进行了实验研究。结果表明,通过输入/输出线性化理论所建立的数学模型,可以有效地判别系统稳定性,同时获取输入电流与阀芯输出位移的关系；利用流固耦合振动模型,可以有效地解释伺服阀高频自激原理,通过实验采集及数据分析得到的伺服阀自激频率及幅值变化趋势与计算结果基本一致,验证了耦合振动模型的准确性；同时通过优化Logistic方程曲线得到阀的优化启闭规律,有效的降低了电液伺服阀油液振动幅值,验证了控制措施的有效性。
[Abstract]:Abstract: the electro-hydraulic servo system with large transmission power, fast response speed, control characteristics, high precision in the aviation, aerospace, shipbuilding and other plays an important role in defense industries. As the core component of electro-hydraulic servo control system of electro-hydraulic servo valve, precision mechanical structure is complex, high precision, its stability, reliability rapid and largely determines the control performance of the electro-hydraulic servo system, and even affect the aerospace mission success. When opening and closing control action, the electro-hydraulic servo system of internal fluid vibration often produce self-excited phenomenon, resulting in a torque motor and the piston to produce larger vibration amplitude, seriously affect the normal work the characteristics of life. Even in a certain type of Aerospace Precision two nozzlebaffle electro-hydraulic servo valve as the research object in this paper, the vibration characteristics of the electro-hydraulic servo valve and the mechanism induced by fluid solid coupling The influence rule of the whole system control is studied in depth, in order to construct a reasonable basic model and further improve the basic theory system of electro-hydraulic servo valve, and finally get the corresponding control measures to reduce or suppress the coupling vibration.
This paper first describes the research background, summarizes the domestic and foreign scholars in the liquid-solid coupling vibration characteristics, research methods, research results of electric hydraulic servo system of the vibration and vibration control, analysis and put forward the key flow problem analysis and control of the coupled vibration in the solid, clear the research direction, objective and the significance, finally determine the technical route of this study.
According to the basic principle of the valve control of the electro-hydraulic servo control system, the static and dynamic characteristics of electro-hydraulic servo valve were analyzed, a nonlinear mathematical model of the double nozzle flapper servo valve, and according to the nonlinear differential control theory, the nonlinear state feedback transformation, the system input / output linearization, and on this basis analyzed the stability of the zero dynamics system. Compared with the linear method based on the basis of the incremental operating point, the linear mathematical model built for analysis of fluid solid coupling vibration and vibration control to provide a theoretical basis, the new model will be closer to the actual control system.
Self servo valve is caused by unsteady flow system, is the dynamic flow parameters of the step change of electro-hydraulic servo valve with nozzle flapper for prestage structure, flow velocity within the nozzle jet, shear flow, precipitation of cavitation, the coupled vibration of fluid induced vibration caused by high frequency often cause Xiao servo valve work is produced. In this paper, combined with the basic theory of fluid mechanics, the nonlinear electro-hydraulic servo valve model as the foundation, established between the flapper nozzle jet flow field model. At the same time through the field test, the actual flow parameters of electro-hydraulic servo valve flow, finally gives the jet pressure pulsation, internal relationship between structure parameters and high frequency self-excited vibration of the three.
Servo valve assembly as servo valve two stage structure, the fluid through the valve port into the valve cavity flow speed relatively slow, the formation of the free shear layer has a larger velocity gradient, the shear separation perturbation in the propagation process by the shear layer instability effects formed by amplification, and passed on the downstream wall the new induced disturbance, formation of self-excited vibration. This paper uses numerical methods on fluid oscillation theory and fluid behavior equation, will flow through the pipeline fluid as a nonlinear system, calculated around the valve or actuator, as the motion of the fluid boundary conditions, the stability limit calculation, we obtain exact solutions of equations, based on analysis of the the structure characteristics and work characteristics, proposes a coupled semi analytic mathematical model. The distribution in order to further study the motion state of the hydraulic system and the parameters of the, According to the actual situation and the movement of the hydraulic system of motion, on the one-dimensional fluid transient theory, considering the change of oil compression on the oil momentum, using the characteristic analysis method, finite difference scheme, numerical analysis of servo valve controlled hydraulic pipeline water hammer, and obtain the dynamic characteristics of tubing through experimental research, results show that the characteristics of the dynamic model can describe the pipeline system better transient.
Finally, through the development of electro hydraulic servo test bench of self-excited characteristics, vibration characteristics of the static and dynamic flow experiments were carried out. The results show that the established mathematical model of input / output linearization theory, can effectively distinguish between system stability, while obtaining the input current and the output displacement of the valve core; the fluid solid the coupled vibration model can effectively explain the servo valve servo valve self high frequency principle, self excitation frequency and amplitude changes with the calculation results obtained by experimental analysis and data acquisition are basically the same, to verify the accuracy of the coupling vibration model and optimization; valve open shut law obtained by the optimization equation of Logistic curve, effectively reduces the power hydraulic servo valve oil vibration amplitude, verify the effectiveness of control measures.

【学位授予单位】：北京交通大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TH137;TB535

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